A serpent-skinned brittle star
Brittle stars can regenerate broken off arms but can get confused when to stop
The underside of the brittle star showing the star-like mouth and the genital slits running alongside the arms
Tiny arms starting to emerge from the parent... (image Geoff Spiby)
... and further out
Tiny stripy baby on the parent's body (image Geoff Spiby)
Genital slits post birth
All images, except where specifically noted, Georgina Jones
Serpent-skinned brittle stars (Ophioderma wahlbergii) are very common on Cape reefs, both on the actual reefs and on the sand around them. They're fairly standard, as brittle stars go, with a smallish round body up to 50mm across, and five snaky arms which may be up to 150mm in total length. They are carnivorous, and if fed will apparently eat until their bodies actually explode. Grisly.
But what's interesting about them is that they brood their young and occasionally the babies can be seen emerging from the genital slits of the parents as the sequence of images shows.
For more details on this species, see "A field guide to the Marine Animals of the Cape Peninsula" available directly from SURG or better dive and book stores in Cape Town.
A field guide to the Marine Animals of the Cape Peninsula, G Jones, 2008
Two Oceans, A guide to the marine life of Southern Africa, GM Branch, CL Griffiths, ML Branch and LE Beckley, revised edition 2010
Thanks to Georgina Jones for the artice and Geoff Spiby for the use of his image!